1. Field of the Invention
This invention relates in general to methods and devices for blending surfactant mixtures and utilizing these surfactant mixtures for treating wells producing heavy hydrocarbons.
2. Brief Description of the Prior Art
Production and pumping of heavy crude oil has long been a problem because of the high viscosity of the crude oil and because of the accumulation of paraffins, tars and other heavy hydrocarbons in the wellbore and tubing. It has long been known that this problem can be somewhat alleviated by introducing a solvent into the crude oil to reduce its viscosity. For example, a kerosene distillate can be pumped through the annulus of the well to the production zone where it mixes with the crude oil from th producing formation. The kerosene distillate reduces the viscosity of the heavy crude oil to make it more easily pumped and it also helps to remove accumulations in the tubing.
A significant disadvantage of using solvents such as kerosene distillate is that such use is often expensive. For example, it may require as much as one-quarter to one-half barrel of kerosene distillate or more to produce one barrel of heavy crude oil.
U.S. Pat. No. 3,241,614 to Burtness, discloses a method of utilizing a surfactant with the solvent for cleaning wellbores. More particularly, a surfactant is mixed with a solvent and injected into the wellbore, followed with an injection of water. The surfactant has both an oil soluble and a water soluble characteristic allowing the water to assist removal of the accumulations in the wellbore. It is also stated that a mixture of solvent, surfactant and water can be injected into the well to prevent further accumulation of the heavy hydrocarbons. In these mixtures, the surfactant may be as high as sixty-five percent by weight of the solvent and the water may be in an amount as high as seventy-five percent by volume of the solvent and water.
The above-described methods are not as satisfactory for improving the production of heavy crude oil from a well as the present invention.